Classical computing using semiconductor devices may reach its physical limits, as suggested by Moore's Law. The industry is currently looking for more and more powerful computers. Therefore, the parallelism of processors and/or threads is pushed forward. However, it is foreseeable that also this approach will reach its natural limitations soon. On the other side, new approaches to computing and data processing based on quantum computing is reaching a stadium in which a higher diversity of devices becomes a requirement.
As known, the model of quantum computation is based on two physical principles: (a) the uncertainty principle, describing that attempting to observe the state in general disturbs it, while obtaining only partial information about the state; (b) and entanglement, describing that two systems scan can exist in an entangled state, causing them to behave in ways that cannot be explained by supposing that each particle has some state of its own.
In classical computing, a storage with n bits may switch from one status (combination of n “1s” and “0s”) to another status. Thus, exactly one status may be taken at a time. In contrast to this, a quantum computing system or storage having n quantum bits (qubits) may take 2n statuses at the same time. It is obvious that those quantum computing systems may be much more powerful and suitable to address problems not approachable by traditional computing systems. As a rule of thumb, it is assumed that problems requiring 50 or more qubits may not be solvable by classical computing approaches at all.
Thus, fault tolerant quantum computing over a large scale remains an ongoing challenge. Topological protection systems without local de-coherence is a strong requirement. Braiding of Majorana fermions has been one of the most promising approaches. However, in currently available nanowire/superconducting hybrid devices precisely tunable local magnetic fields are required on the nanoscale. Recently, a new anyon, the parafermion, with the same potential for topological quantum computing has been proposed. However, parafermions may eliminate each other if they meet, i.e., collide. Therefore, up to now, no device for braiding of parafermions exists.
There are several disclosures related to quantum computing:
Document U.S. Pat. No. 9,517,931 B2 discloses a measurement-only topological quantum computation using both projective and interferometric measurement of topological charge. Various issues that would arise when realizing it in fractional quantum Hall systems are discussed.
Document titled “Quantum Computing with Parafermions”, published in Physical Review B 93, 125105 (2016) by Adrian Hutter and Daniel Loss describes parafermions as exotic non-Abelian quasi-particles generalizing Majorana fermions. In contrast to Majorana fermions, braiding of parafermions with d>2 may allow to perform an entangling gate.
A disadvantage of known approaches may be that currently no device has been demonstrated to allow a controlled handling of the parafermions. A description of such a device is the objective of the current document.